<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Fundamentals</title>
    <link href="resources/threejs-tutorials.css" rel="stylesheet" />
    <style>
    html, body {
      margin: 0;
      height: 100%;
    }
    canvas {
      width: 100%;
      height: 100%;
      display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js",
    "three/addons/": "../../examples/jsm/"
  }
}
</script>

<script type="module">
import * as THREE from 'three';
import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );
	const scene = new THREE.Scene();

	const aspect = 2; // the canvas default
	const fov = 35;
	const near = 0.1;
	const far = 5000;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.x = - 0.;
	camera.position.y = 350;
	camera.position.z = 40.;

	const useFog = true;
	const useOrbitCamera = false;
	const showHelpers = false;
	const camSpeed = 0.2;

	if ( useOrbitCamera ) {

		const controls = new OrbitControls( camera, canvas );
		controls.target.set( 0, 100.01, 0.2 );
		controls.update();

	}

	renderer.shadowMap.enabled = true;

	const hemiLight = new THREE.HemisphereLight( 0xffffff, 0xffffff, 2 );
	hemiLight.color.setHSL( 0.6, 1, 0.6 );
	hemiLight.groundColor.setHSL( 0.095, 1, 0.75 );
	hemiLight.position.set( 0, 50, 0 );
	scene.add( hemiLight );

	if ( showHelpers ) {

		const hemiLightHelper = new THREE.HemisphereLightHelper( hemiLight, 10 );
		scene.add( hemiLightHelper );

	}

	const dirLight = new THREE.DirectionalLight( 0xffffff, 3 );
	dirLight.color.setHSL( 0.1, 1, 0.95 );
	dirLight.position.set( - 300, 220, 245 );
	scene.add( dirLight );
	dirLight.castShadow = true;
	dirLight.shadow.mapSize.width = 2048;
	dirLight.shadow.mapSize.height = 2048;
	const d = 350;
	dirLight.shadow.camera.left = - d;
	dirLight.shadow.camera.right = d;
	dirLight.shadow.camera.top = d;
	dirLight.shadow.camera.bottom = - d;
	dirLight.shadow.camera.near = 100;
	dirLight.shadow.camera.far = 950;
	dirLight.shadow.bias = - 0.005;

	if ( showHelpers ) {

		const dirLightHeper = new THREE.DirectionalLightHelper( dirLight, 10 );
		scene.add( dirLightHeper );

	}

	const loader = new GLTFLoader();
	const camRadius = 600;
	const camHeight = 160;
	const camTarget = [ 0, 30, 0 ];
	const fogNear = 1350;
	const fogFar = 1500;
	loader.load( 'resources/models/mountain_landscape/scene.gltf', ( gltf ) => {

		gltf.scene.traverse( ( child ) => {

			if ( child.isMesh ) {

				child.castShadow = true;
				child.receiveShadow = true;

			}

		} );
		scene.add( gltf.scene );

	} );

	window.s = scene;

	if ( useFog ) {

		const vertexShader = `
    varying vec3 vWorldPosition;
    void main() {
      vec4 worldPosition = modelMatrix * vec4( position, 1.0 );
      vWorldPosition = worldPosition.xyz;
      gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
    }
    `;

		const fragmentShader = `
    uniform vec3 topColor;
    uniform vec3 bottomColor;
    uniform float offset;
    uniform float exponent;
    varying vec3 vWorldPosition;
    void main() {
      float h = normalize( vWorldPosition + offset ).y;
      gl_FragColor = vec4( mix( bottomColor, topColor, max( pow( max( h , 0.0), exponent ), 0.0 ) ), 1.0 );
    }
    `;

		const uniforms = {
			topColor: { value: new THREE.Color( 0x88AABB ) },
			bottomColor: { value: new THREE.Color( 0xEFCB7F ) },
			offset: { value: 730 },
			exponent: { value: 0.3 },
		};
		uniforms.topColor.value.copy( hemiLight.color );
		scene.fog = new THREE.Fog( scene.background, fogNear, fogFar );
		scene.fog.color.copy( uniforms.bottomColor.value );
		const skyGeo = new THREE.SphereGeometry( 4000, 32, 15 );
		const skyMat = new THREE.ShaderMaterial( { vertexShader: vertexShader, fragmentShader: fragmentShader, uniforms: uniforms, side: THREE.BackSide } );
		const sky = new THREE.Mesh( skyGeo, skyMat );
		scene.add( sky );

	}

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const width = canvas.clientWidth;
		const height = canvas.clientHeight;
		if ( width === canvas.width && height === canvas.height ) {

			return false;

		}

		renderer.setSize( width, height, false );
		return true;

	}

	function render( time ) {

		time *= 0.001;
		time += 80;

		if ( resizeRendererToDisplaySize( renderer ) ) {

			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		if ( ! useOrbitCamera ) {

			const angle = Math.sin( time * camSpeed ) + Math.PI * .75;
			camera.position.set( Math.cos( angle ) * camRadius, camHeight, Math.sin( angle ) * camRadius );
			camera.lookAt( ...camTarget );

		}

		renderer.render( scene, camera );

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();
</script>
</html>
